Phase 2: Phase 2 starts when the patient is randomized to a second medication, i.e., olanzapine, quetiapine, risperidone, or citalopram. Patients will be randomized from an antipsychotic treatment to another antipsychotic treatment or citalopram in the ratio 3:3:2, or from placebo to an antipsychotic treatment or citalopram in the ratio 1:1:1:3 respectively. Therefore, 50% of patients who took placebo in Phase 1 will be randomized to an antipsychotic in Phase 2, and 50% will be randomized to citalopram in Phase 2. After the initial two weeks in Phase 2, the investigator can move the patient to the next phase, due to lack of efficacy or tolerability. After the patient has been on the Phase 2 study drug for approximately 12 weeks, the investigator can decide whether the current medication is sufficiently optimal or whether it would be more beneficial to try another randomized medication.